A biscuit which polar explorer Ernest Shackleton handed to a starving fellow traveller on an expedition more than 100 years ago has sold at auction in London for 1,250 pounds (almost $2,000).

The biscuit, one of thousands which formed the staple diet for Shackleton and his companions on the 1907-1909 Nimrod expedition, failed to reach its top catalogue price of 1,500 pounds ($2,390) at Christie's.

Made especially for the expedition by British company Huntley and Palmers, the biscuits were fortified with milk protein to help the group on their arduous journey.

The explorers were forced to turn back after battling to within 160 kilometres of the pole.

Their return journey became a race against starvation, with the group surviving on half rations.

At one point Shackleton handed fellow explorer Frank Wild one of his own biscuits, prompting Wild to record in his diary: "Thousands of pounds would not have bought that biscuit."

The biscuit was left at the hut at Cape Royds in the Antarctic where Shackleton was based during the expedition and is perfectly preserved.

Nicholas Lambourn, a director at Christie's, said ahead of the auction that the biscuits were designed to provide the explorers with maximum stamina but they lacked a crucial ingredient.

"They had a special recipe in an attempt to produce the right amounts of protein and carbohydrate," he said.

"But they didn't understand the importance of vitamin C, they weren't perfect."

In 2001, a biscuit from another Shackleton expedition sold for 7,637 pounds at auction, even though just several crumbs remained.